Define return value in Spark Scala UDF

Question

Imagine the following code:

def myUdf(arg: Int) = udf((vector: MyData) => {
  // complex logic that returns a Double
})

How can I define the return type for myUdf so that people looking at the code will know immediately that it returns a Double?

Answer 1

I see two ways to do it, either define a method first and then lift it to a function

def myMethod(vector:MyData) : Double = {
  // complex logic that returns a Double
}

val myUdf = udf(myMethod _)

or define a function first with explicit type:

val myFunction: Function1[MyData,Double] = (vector:MyData) => {
  // complex logic that returns a Double
}

val myUdf = udf(myFunction)

I normally use the firt approach for my UDFs